Telegraph transmission of signals



Dec. 11; 1928. 1,694,769

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Dec. 11, 1928. 1,694,769

L. CASPER TELEGRAPH TRANSMISSION OF SIGNALS Filed Aug. 1. 1921 7Sheets-Sheet 6 Line:

Dec. 11, 1928. 1,694,769

L. CASPER TELEGRAPH TRANSMISSION OF SIGNALS Filed Aug.l. 1921 7Sheets-Sheet '7 47 35a I A 'l 15- *d rd '6 U x *i z E Q 4! Patented Dec.11, 1928.

LOUIE: CASPER, OF BROQKLYN, NEW YORK.

TELEGRAPH TRANSMISSION OF'SIGNALS.

Application filed August 1, 1921. Serial No. 488,914.

My inventionrelates to improvements in means for the correction ofdistortions oi signal waves or the like during their procsee oftransmission over a line wire, and has for its object to provide asimple eliicient arrangement inexpensive to install or maintain wherebysignal waves during their proc ess of transmission over a line wire mayretain as nearly as possible their original contour. In attaining thisobject, my invention as far as I can ascertain, acts in a dual capacity,first, in draining extraneous induction from such circuits to whichitapplied; and, second, in improving the shape of the waves as they arebeing transmitted over a line wire or cable that is subject to variablefactors of inductive interference or attenuation, and for the reasonscited it has a value in its application upon circuits where it isdifficult to obtain a duplex balance, as for example, in case of aloaded submarine cable onwhich duplex or simultaneous operation in bothdirections is being attempted.

To these ends my invention consists in the combination o1 elementshereinafter more particularly described and definitely pointed out inthe claims.

teiterence is had to the accompanying drawings forming a part of thisspecification in which corresponding letters of refer ence in thedifferent figures indicate like parts.

Referring .to the drawings. Fig. 1 is a side view of the inductionarrangement. Fig. 2 is a detail of Fig. 1, showing a. crosssection on aline 5 5 of commutator 6. Fig. 3 is a similar detail showing across-section on a line 6-6 of commutator 7a Fig. 4 shows variousmodifications of the arrangement as applied to a series of parallellines. li ig. 5 ilhr' ra'tes a method of applying the a merit to abridge type duplex telecircuit. Fig. 6 shows a modification oi' thedrainage arra igement, the same being a plicable to either differentialor bridge type duplex telegraph circuits.

Figs. 7, S and 9 are schematic drawings showing various methods ofbridging across a main line relay with the arrangement in cluded in thebridging connections.

Fig. 10 shows the principlein a duplexed circuit connected directly inthe-line. Fig. 11 shows a modification of the-principle, applicable inlieu of the scheme shown in Fig. 10. Fig. 12 is a modification ofFigl'l.

Fig. 18 represents a partial View of a modification of commutators 5 and6 shown in. Figs. 2 and 8. This modificationcomprises theequivalent ofthe two latter commutators combined into one face plate for betterillustration. This figure furthermore shows the manner in which atransmitted signal or pulse over a line is subjected to innumerablebreaks; also showing the manner in which the line is grounded on oneside of the same simultaneous with the breaks aforementioned.

Fig. 14- illustrates graphically the claritying effects of the breaksand grounds upon a signal during its course of transmission upon a linewire as it approaches the receiving apparatus.

Fig. 15 illustrates a line with transmitting and receiving apparatus atstations A and B and is also equipped with drains for extraneouscurrents at stations C and. D.

Fig. 16 graphically illustrates the effects of the arrangement locatedon the line as shown in Fig. 15 upon distorted signals flowing on saidline, smoothing out the distortions be fore the signals arrive at eachof the terminals.

Referring to Fig. 1, 2 is a motor which may be either direct oralternating current type, having a shaft 3 and is supported at one endof said motor by end bearing 4:. Said end bearing rests on insulatedplate 24; at its base which insulates said end hearing from the metalbase 5 as shown. Attached to the shaft 3 are commutators G and 7. 'Theshaft 3 is split and joined together by a collar 8 which is made up ofsome non-conducting material. This insulates the commutators 6 and 7from each other. 29 is a brush holder inside of which is a brush 31, thesaid brush bears on commutator 6.

28 is a brush holder having a brush 30, the said brush bearing oncommutator 7. 10 is a projection, .securedto the motor frame by screws 9and which supports the brush holders 29 and E28. '13 is a combinedbrush.

and holder, the brush of which also bears on shaft 8, but as alreadyindicated. is not in -ic contact with that section of shaft 3 on whichthe brush and holder 13 are in contact. 14 is a brush and holder.

These latter two brushes constitute elec trical conducting mediumswhereby the current passes through the metallic portions of commutatorsand 7, and affords a direct path for the current to pass from either thebrushes 29 or 28 through the commutators aforesaid to the ground 15 atbinding post to the operating set oi apparatus 22 at binding post 16,respectively.

17 are metallic :e ments of commutator 6. 18 are insulated sectionsbetween the segments 17. 19 are insulated sections on commutator 7. 20are narrow metallic segments between insulated sections 19.

The operation of the arrangement as shown in Fig. 1 is as follows:

The commutators 6 and 7 on shaft 3 revolve at a high rate of speedimpelled by motor 2. The line wire is connected to binding screw 21which makes electrical connection with metallic projection 10 and inturn with brush holders 29 and 9. As shown in cross-section in Fig. 2,the commutator 6 is made up of metal except the insulated sections 18.The commutator 7 is likewise made up of metal except the insulatedsections 19 shown in detail in Fig. 3.

he current from the line 25 passes through the commutator 6 and fromthence through the brush holder combination 13 to the terminal apparatusset at 16 except when interrupted by the insulated sections 18. Theseinterruptions owing to the high revolving speed of the commutators areoi momentary duration, so short in fact that there is very littleperceptible difference in the regular line current flow due to theseinterruptions o momentary breaks. At the instant the breaks occur in thecommutator 6, a connection is made from the line to the ground 15through the commutator 7 by means of segments 20 of the lattercommutator. This has the efiect of momentarily grounding the line eitherthrough a condenser or a resistance at the exact instant when the breakin the line connection is made by the insulated sections 19 incommutator 6.

The effect oi this arrangement is twofold: First. the regular currentflowing on the line in obedience to, and as a result of. an impressedelectromotive force directed W a transmitting medium either hano orautonnilically operated at either or both of the line terminals willtend to follow its regular channel, that is to say, the current willflow beginning from the grounded generator at one end of the line to theapparatus at the other end of the same to the ground thus completing itsregular circuit. The momentary interruptions or breaks make no materialdiii'erence in this regular circuit low except to slightly reduce thecurrent amplitude which is not important when it is taken intoconsideration that the circuit is drained of extraneous currentinterference by reason of this arrangement.

ll ith such foreign currents that have induced themselves on the line,the flow of the same is diilerent from that of the regular line tlow.These extraneous currents are up from variety of causes as has alreadybeen intimated and are generally extremely erratic in frequency and intosity. The tendency of these currents is to discharge themselves in thecase of grounded circuits to earth at such periods when the regular mainline current is at its lowest value and does so in ZtCCOl'Clftl'lCG withOhms law by following the path of the least resistance.

, bet.-

A ready path is provided for these extraneous currents to flow directlyto earth when the line is actually out through the break caused by theinsulated sections 18 and a ground conductor provided through thesegments 20 which are in exact synchronous relation with the aforesaidinsulated sections 18.

The extraneous currents quickly discharge themselves through theconducting medium momentarily presented as described and be fore theycan build themselves up again to an approximate maximum value, the drainconducting medium as described above, presents itself again and asalready stated is of such short duration as not to ailect the regularsignals flowing on the line.

The second effect of this arrangement is to break up the harmonic factorin such cases where a number of parallel lines as shown in Fig. a,operate with. current coming from one generator at one or both of theterminal stations oi said parallel lines. The commutator of themotor-generator is diviced up into a number of conducting segments. eachsegment being insulated from its neighbor. These insulated sectionscause a ripple flow of current due to the m0- mentary rise and fall ofthe potential because of the insulated breaks between tee conmiutatorsegn'ients stated. In this manner all parallel wires thus connected uphave ti o same ripple current flow which tends to create between suchparallel wires a harmonic eil'ect and by reason of such effect, willproduce a certain amount of mutual induction. The mutual industanceproduced by the foregoing is comparatively slight to be sure. but isnevertheless a limiting factor towards the attainment of greatereiiiciency in the carrying capacity of parallel telegraph lines.

The introduction of individual connnutaparatus '38.

tors .6 in series with each of the parallel wires and each commutatorrevolving at slightly different speeds will have the effect of breakingup the harmonic ripple referred to.

In further reference to l ig. a. Three 1 .el lines, 37, 38, 39 areshown. All tl ee lines obtain current supply from grenorator throughresistances 36, .36", .36. On each of the three lines diilerei-itmethods of connecting up the arrangement are shown. On line 3'? thedrain arrangement consists of connnu-tators =6 and 7. ti e former beingconnected directly in the line through brush holder 29 and brush 31.."commutator 7 taps the line 37 through brush holder 28 and brush SO andprovides a momentary path to earth through resists-nae 40 and condenser"Llhe period when this momentary path occurs is simultaneous with aperiod when the line is opened. momentarily by means of commutator (S.The regrnlar ine current flow is shown by the double feathered arrowwhich with the aid of the drain provided by commutator 7 is cleared ofinterference by providing a ready path of escape to earth for the latterat a time when the regular line circuit is interrupted. The singlefeathered arrow shows the current cleared of extraneous currentinterference flowing toward the receiving apparatus 37.

Line '38 is similarly equipped with an inductance drain arrangementhaving a resistance 33 in series with the line between the drainarrangement and the receiving ap- This resistance may be eitherinductive or non-inductive.

The resistance 33 is desirable in certain cases to act as an impedanceto the incoming interference. This interference is afforded momentarilya better and less impeding path to the earth through commutator 7 andresistance 41, simultaneously with the momentary opening; of the linethrough commutator 6 in a manner similar to that described in referenceto wire 8?. SS indicates the receiving apparatus in circuit with .line88.

Line 39 is likewise equipped with the in- (luctance drain arrangementsomewhat modilied. The inductance coil 8s bridges the drain which hasthe eilect of impeding the flow ot the current toward station A. Thischeck is momentary and occurs when the insulated sections 18 ofcommutator 6 break the continuity of current flow through saidcommutator to terminal A. At that instant two paths for extraneouscurrents are presented, via, one through the inductance and the otherthrough a metallic segment in commutator 7 to earth through condenserThere being no material impedance in the latter path, the extraneouscurrents will more readily flow through it rather t-hanthrough theinductance .34. 39

repr ents the recei ing apparatus in series with line :39, the formermay be either a .y. printer, telephone receiver or other similar device.

Referring to Fig. 5, a2 is a telegraph poleona-nger which alternatelysends currents of different polarities :to the line by means ofgenerators 35 .35", the currents from which flow through resistances 3.6and 36. l-3

and -44 are resistance arms of a bridge able condenser (to compensatefor the capacity of the line. .58 is the apex or battery split.

The wave correcting arrangement is likewise bridged across zresistancearms as and illhis anrangement consists of resistances 4:9 and 49 and atthe center oi both resistances :at'oresaid a tap is made with brushholder 29 and brush .31 to commutator 6. lhe brush connects withadjustable condenser and thence to earth as shown.

The commutator Z is likewise tapped between the adjustable condensers:50 and :50 which are ibridged across the bridge resistances d3 and 4a.The tap connection for commutator 7 is made with ibrush holder 28 andbrush 30 which bears on the commutator 7 aforesaid. The brush 13connects with adustable resistance Y51 and from thence to earth 15.

The operation of the arrangement as shown in '5 is as follows:

The incoming current meets with impedance in the combination of thecoils of the polar relay l5 and bridge arm 48. rent, however, meetsmomentarily with less impedance to earth through resistances l9 and 4:9,assuming of course that the commutators 6 and 7 are revolving. A certainportion of the main line current will momentarily how to the earththrough the ad justable condenser 52. The character of the currentflowing through the circuit includ ing the condenser 52 as described,would be in the nature of electrostatic induction. Such path ispreferable to two other branch paths leading to earth, one by way ofbridge resistance 43 and the other through the polar relay A furtherdrain for extraneous currents is provided by conunutator 7. At theperiods when the brush 3O bears on the in sulated sections ofcomn'iutator 7, a path is provided by the bridging; connection whichincludes the adjustable condensers 50 and 50 thatofi'er considerableimpedance to the current ,liow due to the fact that" both condensers 50and 50 are in series with each other which reduces the capacities of thecondensers to the sum of the reciprocal of The -cur- I the condensersaforesaid. When, however, a segment is in momentary contact with thebrush 30, a grounc tap connection is made at the center of the bridgingcircuit between the condensers 50 and 50 which places the condensersaforesaid in parallel flowing toward the earth as shown. This at oncebuilds up the capacity of the two condensers 50 and 50 to their ratedindividual values.

In this manner a substantial path is previded "for extraneous currentsto flow momentarily to ear h from the line in the manner described.

A further improvement is effected by so arranging the segments ofcommutator 6 that the instant the drain path is interrupted by saidcommutator 6 in connection with the bridging circuit connected thereto,a connection is made with the earth through commutator 7 in connectionwith the bridging circuit with which the commutator 7 is tapped.

In this manner both the bridging circuits to which con mutators 6 and 7are respec tively attached alternately provide an inductance drainagepath to earth and d es so without disturbing 0r retarding the normalaction of the main line relay.

Referring to Fig. 6 which diagram cally illustrates a terminadifferentia duplex apparatus set. its in Fig. 5. polechanger whichalternately COHDQCLS gencraters 85" through resistances 36 36 to themain and artificial lines through the split 53 at mil-ammeter 5a. theartificial line side passing from the right hand connection of saidmil-ammeter through artificial line coil 55 to artificial lineresistance 41-? to earth 15. Artificial line capacity 4L8 is connectedup as shown. T he line side of the duplex circuit passes from the lefthand side of inil-amnieter 5% to the line coil 56 of polar relay andfrom thence to line The drainage ar ingeinent is bridged across the mainline and artificial line coils as shown and is somewhat modified overthe arrangement shown in Fig. 5 in that two brushes bear on theperiphery of each of the commutators 6 and 7. From the line sideterminal of coil 56, the coil tS is connected and which in turn isconnected to brush holder 29 and brush F1 in the artificial line sideterminal of coil connected to coil l9 and which in tu n connected tobrush holder 29 and brush 31. The brushes ill, 31"" bear on commutator('3. The brush it bears on shait 3 and is in connection with the earthi5 throi h condenser Fr the terminal of cor another conne ion made tocondenser and from trance to brush 30. from the terminal of coil 56another connection is made to condenser 50" and from th ice to brush 3b.The brush 1. -3 bears on shaft 3 and is in connection with the earth 15through resistance 51.

The method oil operation of this ar -angemeet is as follows:

The current coming in from the line is partially diverted through thecoil l9 passing through the brushes 31 31"" at a time when aforesaidbrushes bear on a metallic segment on commutator 6. i hen this oc cursthe current passes on through coil 49 and artificial hue resistance 47to earth 1". buntutancously, connection is made with sl 3 which is inmetal ic connection with ial segments .1? making an earth connectionthrough condenser 52.

This has the effect draining extraneous currents from the line w thoutunbalancing or retarding the polar relay a5.

fin additional drain is also provided by the commutator 7 whichalternates in eiiect with the drain circuit incl ding commutator Thiscircuit comprises a bridge across relay connected up as described and isective when the brushes 30, 30 simultaneously bear on one of themetallic segments 20 on commutator 7. When this occurs a pan "on ofcurrent from the line passes "cross the bridge circuit to earth throughor "cial coil il-7. Another path is provided shaft 3 which is inmetallic connec- "ion r-riththc segments 20 0t commutator 7 :rhicl leadsto earth through adjustable resist nee 51.

hase two drains while acting distinctly er-native action through..cities and resistances together "h diil'erent contact intervals andalternatin interrupting periods through which curincoming signal ofextraneous current or eher interference and with a minimum of l ag tothe polar relay 4:5 and without unbalancing the same.

ig. T is illustrative of a schematic modiation of the drainagearrangement as apilied to a polar relay. 35 the generator ither positiveor negative, earthed at one terminal. The other terminal of saidgenerater passes through the artificial line coil thence to artificialline resistance to earth o i si e. On the other side the generator 35 tough the line coil 56 to the line The air igement brid ed across the nline and artificial line coils as shown. lent consists of? two separate1; the lll'tjb irom the artificial line coil side to condenser 50 tobrush 31 to condenser 50 to the line coil The brush 31; connects with or(S which connects wi h the earth tnlillilllt the brus i is in contactwith metaln 1T thence to shaft 3 to tests 5 and ground 15.

.wtificial coil 50 to resistance 49 to 31, to resittance a9 and to theterminal side of line coil 56. The brush 31 connects the commutator 7 toearth when one of the metallic segments 20 of said commutator 7 is incontact with brush 30 which permits a path through shaft 3" brush 13 andcon denser 52. 1

The effect of this arrangement is similar to that described in Fig. 5and may be applied in such cases when the extraneous currents or otherinfluences are of such a char actor that this particular method wouldrespend most beneficially.

Fig. 8- is another modification and is shown schematically as in Fig. 7.In this arrangement the ground drain is through the artificial lineresistance as'one path and the coils 55 and 56 through the generator toearth 15 as another path. 1:9, 19*, 49 are resistance coils in the draincircuits. is an adjustable condenser in series with the circuitincluding the comutator 7.

F 9 is another modificat on shown schematically. Across the main lineand artificial coils 55, 56, two extraneous current drain branches areprovided. The first branch passes from the terminal side of artificialline coil to adjustable condenser 50 to brush 31 to commutator 6 toinductive resistance 49 to the terminal side of the line coil 56. Thesecond branch passes from the terminal side of artificial line coil toresistance 49 to brush of commutator '7 to resistance 49 to the terminalside oi the line coil A. ground path is provided at the ohmic center ofthis latter branch from the brush 30 through commutator 7 to earththrough condenser 50 and 49 the latter condenser and resistance shown inparallel. The condenser 50 and 19 may also be operated in series toearth. T he above arrange ment is applicable in cases where there isconsiderable extraneous power current.

In Fig. 10, a diagram of a telegraph polar duplex is shown. 35, 35 aregenerators which in turn impress current into the circuit controlled bythe polechanger 42. The current from either of the above mentionedgenerators passes through the split point 58 at the mil-ammcter anddivides into two branches, one branch flowing throiiurh the artificialline coil 55 of relay 4C5 to compensating resistance 4:7 and artificialline resistance 47 to earth 15. The second branch flows from the splitthrough line coil'56 of relay 4:5 to the line 45. T he induction drainarrangement is connected in at some section of the line 46 as shown. Thecurrent from the line flows through brushes 30, 31. The flow throughbrush 31 passes through the revolving commutator 6 to shaft 3 to brushlet and from thence into the receiving relay 45. The action of thedrainage arrangement is similar to that described in Fig. 4. In suchcases where the drainage arrangement is connected. up as shown, it isecessary to compensate in the artificial line of said polar duplex forany impedance created by the drainage arrangement connected in somesection of the line. the resistance 17 and condenser 48 both of whichare adjustable as to: inductive reactance in the case of the resistance17 and capacity reactance in the case on": the condenser e8.

Figs 11 and. 12 are other modifications of the drainage arrangement. Theaction of the commutators 6 and 7 is similar to that shown in Fig. ldescribing the action of the err eous current drain on the line wire 37in said: figure; The ground drain through commutatc G'lft'GQ l throughtwo carbon or grapliite L l lltl'tLS 59 59 in series between the briuaof commutator 7 and the earth in Fig. 12 or through condenser 52 andresistance 51 in Fig. 11. Connected between the graphite cylindersaforesaid is a condenser (50 the opposite terminal of which leads to theearth 15.

The action of the graphite cylinders in Fig. 12 in connection withcondenser 60: is as follows:

The graphite cylinders have comparatively high ohmic resistance but amaximum surface in and outside of the cylinders aforesaid. The characterof the extraneous currents to be drained is such that they are moreinclined to flow on the surface 0t such a conductor; thus, the largerthe surface the better the path provided for the tlow 0t extraneouscurrents.

l1, then a conducting path is provided for such extraneous currentshaving a maximum surface and a high ohmic resistance as described, theresulting ettect would be that the regular line flow would be retardedin its flow to earth by ay of the graphite ndcrs. due to thecomparatively high re- :e of the same. it the same time,

/ ira eous currents having litno "enctratirc e ect .tlow along the .4.ice with greater facility regardot the high resistance of the e "211path ance graphite condenser 60 is intended as an additions path in suchcases where extraneous currents will not readily flow through bothgraphite cylinders and 59". There may be any number of graphitecylinders and intervening condenser paths to the ground; Fig. 12 merelyillustrates the method of employing a condenser in this connection withonly two cylinders.

l he arrangementjust described well as the drain arrangements shown inFig. 4 are applicable to any multiplex or quadruplex telegraph circuitand are also applicable to telephone circuits: of the latter, groundedcircuits in particular.

In further reference to Figs. 13 and 14.

This is done by A transmitted signal passing along a line is beingcontinually broken through the action of brush 31 wiping againstsegments 17 and 20. The brush 31 is connected to holder 29 which in turnis connected to shaft 3 which is revolved by a motor similar to motor 2,Fig. 1. The shaft 3 in turn is connected electrically to the line 25 asshown. All the segments 20 which, as already stated, have a smallercontact surface than segements 17, are grounded. Segments 20 areconnected together electrically as shown. When the brush 31 is revolvingwhich would necessarily have to be at a high rate of speed, it passesover both segments 17 and 20. The intervening insulation 18 between thesegments causes a momentary break in the continuity ot the signal, andat a point during the period oi? this momentary break in the signal, oneside of the line is grounded while the other side of the line 22, i. e.,the side nearest to the terminal station, is opened. The duration of thegrounding of the line, as it has already been stated, is eX- tremelysmall occurring only while the brush 31 is passing over segements 20 andis not sutticient to interfere with the functioning of the signal on itsarrival at the receiving end.

This is further exemplified by the graphic diagram in Fig. 14. The curve61 illustrates a signal wave as would appear on an oscillograph, andwhich we will assume to be positive, rising from the zero line to itscrest then falling back to the Zero line again in response tomanipulations of the distant battery through the controlling medium of atransmitter. Owing to parallel or other induction impressing itself upona line, the signal as shown by curve 61, loses much of its normalcharacteristic, being in this case considerably distorted because ofsuch induction. In some cases, of course, the dis tortion is less thanshown in curve 61 and in other cases it is even greater.

The effect of tile introduction of numerous openings simultaneous withthe momentary grounding of the line tends to make the signal curve moreconsistent and is therefore more readily translatable by whateverapparatus is connected to the line circuit at its receiving terminal.

From the foregoing it is seen that a means is provided to improve thereception of signals on a line wire and these means are not necessarilyassociated with either the transmitting or receiving apparatus at eitherend of the line.

Referring to Fig. 15. In this figure the line 46 is shown with terminalap iaratus which in this case is that of an ordinary polar duplexprovided with a polarized relay 45, artificial line 47, polechanger 42and generators 35 35 7 At stations C and D are located extraneousinduction drain arrangements which drain such induction that is inducedfrom the parallel wires PVT in the manner already described. Theinduction drain arrangements are apart from that of eitherthetransmitting or receiving apparatus in the circuit and the former isintended to care for extraneous currents mainly.

Fig. 16 is a graphic illustration showing distorted signals on the lineand the effect upon such signals after the induction drain arrangementshave acted upon them, the gein eral efi ect being to change the shape ofthe wave tor the better reception or signals at the terminals.

It will readily be seen that my invention is capable of considerablemodification without departing trom the principles thereof. or instance,the commutators 6 and 7 may be stationary and the connecting brushes mayrevolve. The brushes may also be arranged to revolve bearing on the sidesurface of the coimnutators 6 and 7 instead of the periphery of thesame.

Having thus described my invention, what I claim is:

1. In a telegraph circuit or the like to which is included one or morearrangements for draining currents induced upon said telegraph circuitby parallel wires, said drain arrangement or arrangements located on theline circuit ahead of the operating a paratus at either terminal of saidtelegraph circuit; said drain arrangement or arrangements consisting ofacircuit interrupter connected directly into the line together withmeans for grounding the circuit simultaneously with the opening thereof;said combined interrupting and grounding arrangements op eratingindependently oi either the transmission or repeption ot' the regularline signals.

2. In a telegraph. circuit or the like to which is included one or morearrangements for draining currents induced upon said telegraph circuitby parallel wires, said drain arrangement or arrangements located on theline circuit ahead of the operating apparatus at either terminal of saidtelegraph circuit; said drain arrangement or arrangements consisting ofa rotating segmented interrupter connected directly with the linetogether with means for grounding the circuit simultaneously with theopening thereot; said interrupting and grounding arrangement orarrangements operating independently ot the transmission or reception ofthe regular line signals.

3. In a duplex telegraph circuit or the like, a bridging arrangementacross the main line and artificial line coils of the main line relay orrelays insa-id telegraph circuit; said bridging arrangement consisting0'? means whereby the incoming current from the line flowing across saidbridging arrangement ell) may be momentarily interrupted simultaneouslywith means for providing a ground path during such momentaryinterruptions.

4i. In a duplex, multiplex or similar telegraph circuit to which hasbeen added a rcsistance medium in parallel connection with a joint path,one branch of said joint path consisting of an arrangement formomentarily interrupting the current flowing in said branch; and asecond path having means for momentarily providing a ground connectionwhereby foreign or extraneous currents may have full and free flowthereto during such momentary periods and means for compensatingartificially for the effect created on the line of said circuit by thecombined resistance medium, momentary interrupting means and momentarygrounijling means aforesaid.

5. In a duplex telegraph circuit or the like, a bridging arrangementacross the main line receiving relay or relays in said telegraphcircuit, said bridging arrangement consisting of a resistance medium anda ca pacity medium, means for momentarily grounding said resistancemedium and means for momentarily grounding said ca pacity medium.

6. In a duplex telegraph circuit or the like, a bridging arrangementacross the main line receiving relay or relays in said telegraphcircuit, Said bridging arrangement consisting of a resistance medium anda capacity medium means for momentarily interrupting the current flowingthrough said resistance medium. and means for momentarily grounding saidcapacity medium.

7. In a duplex telegraph circuit or the like, a bridging arrangementacross the main line receiving relay or relays in said telegraphcircuit, said bridging arrangement consisting oi a resistance medium anda capacity medium; means for momentarily in: terrupting the current flowthrough said resistance means and means for momentarily interrupting thecurrent flow through said capacity means.

8. In a telegraph circuit or the like through which a normal currentflows said normal current operating apparatus at either or bothterminals of said telegraph circuit; means for providing momentarily aground path tor said current simultaneous with the momentaryinterposition of a resistance medium in said telegraph circuit.

9. In a line conveying current forcommunication purposes anarrangementor arrangements for draining induction coming from parallelwires connected to said line; said drain arrangement or arrangementsacting as a unit independent of the terminal operating apparatus on saidline; said induction arrangement or arrangements consisting of asegmented interrupter means which momentarily interrupt the regular linecurrent flow simultaneous with segmented interrupter means whichprovides a momentary ground path for said line.

10. In a telegraph circuit or the like, a IQYOlVlIlg commutator meansconnected to said telegraph circuit which momentarily provides a groundpath for the current flowing in said circuit and a revolving commutatormeans that momentarily introduces a resistance medium in said telegraphcircuit simultaneous with the aforesaid momentary grounding of saidtclegrapl'i circuit.

11. In a duplex telegraph circuit or the like, a revolving commutatormeans connected to said telegraph circuit which momentarily provides aground path for the current flowing in said circuit and revolvingcommutator means that momentarily introduces a resistance medium in saidtelegraph circuit and means for compensating artificially for theresultant eiiect created in such telegraph circuit by the combination ofsaid revolving commutator means that introduces momentarily a resistancemedium and revolving commutator means which momentarily provides aground path for the current flowing in the aforesaid telegraph circuit.

12. In a duplexed telegraph circuitto which is included one or morearrangements for correcting signal wave distortions or for counteractingeffects upon transmitted telegraph signals from extraneous inductiveinterference; said arrangement or arrangements consisting of circuitinterrupting means, said interrupting means operating asynchronouslywith respect to and independent of regular signals passing over saidtelegraph circuit; and means for grounding the circuit at the moment itis opened between said asynchronous interrupting periods.

13. In a line conveying current for com munication purposes, aninduction drain arrangement connected to said line, said induction drainconsisting of means for momentarily interrupting the current flow insaid line simultaneous with means for momentarily providing a groundpath for said line, said ground path consisting of a medium ofcomparatively high resistance but having a maximum surface, saidmomentary ground path being in addition to the regular ground pathforming a part of the circuit including the line aforesaid.

LOUIS CASPER.

